How to filter out rows that start with a certain value in R?-CodePudding

I have a data set like the one below

ID	col1	col2
1	042	10
2	353	13
3	403	03
4	642	22

I want to filter out only the rows that have a value in col1 that start with 4. This includes row1 that has 04, but does not include row 4. Col1 is a character column.

The final data set should look like this.

ID	col1	col2
2	353	13
4	642	22

Thanks!

CodePudding user response：

You may try

library(dplyr)

df %>%
  filter(substring(as.numeric(col1),1,1) != "4")

  ID col1 col2
1  2  353   13
2  4  642   22

CodePudding user response：

We can combine str_detect with filter using the regex '^0 4|^4' that indicates starts with 0 one or more times followed by a 4 or starts with 4.

code:

library(tidyverse)

df <- read_table("ID    col1    col2
1   042 10
2   353 13
3   403 03
4   642 22")


df %>% 
  filter(!str_detect(col1, '^0 4|^4'))
#> # A tibble: 2 × 3
#>      ID col1  col2 
#>   <dbl> <chr> <chr>
#> 1     2 353   13   
#> 2     4 642   22

^{Created on 2021-11-24 by the reprex package (v2.0.1)}